Throughout the history of radio, receivers and their component blocks have been considered to exist within the realm of small-signal circuit design. Metrics such as ICP1 (compression point) were meant to denote regions of operation to be avoided and typically limited the maximum signal handling of the receiver input at nearly any frequency offset to far less than 1V. Although receiver linearity has been the subject of much study, the typical design procedure has been to constrain the system to consist of intentionally linear circuit blocks, hence only requiring the consideration of 2nd and 3rd order nonlinear terms as nonidealities at or near the receiver noise floor.
What is needed, therefore, is a radio that can handle the presence of higher-order intermodulation (IM) products beyond IM3.